Have you thought about buying the thick socks, and sewing something on the bottom to make them nonskid? They probably have something you could iron on as well, I would check at a haberdashery, John Lewis has a GREAT one, which I was happy to find, and the prices are decent, and the salespeople SUPER helpful!! I would just give a salesperson the idea, and see what they could come up with. You wouldn't have to be much of a sewer, and would not need a machine, if you can do a hem, or button, you could sew something onto socks!! You could even do her name, or a little saying, or something. Even just putting a bit of the rough part of velcro would probably work.